Flash Flood Warning 5, NWS Reno, NV

760 
WGUS75 KREV 010051
FFSREV

Flash Flood Statement
National Weather Service Reno NV
551 PM PDT Wed May 31 2023

CAC003-051-NVC005-010101-
/O.EXP.KREV.FF.W.0005.000000T0000Z-230601T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Alpine CA-Mono CA-Douglas NV-
551 PM PDT Wed May 31 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM PDT THIS EVENING FOR 
ALPINE, NORTHERN MONO AND DOUGLAS COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3879 11966 3881 11963 3880 11959 3881 11953
      3876 11952 3871 11944 3868 11949 3867 11953
      3869 11957 3866 11960 3867 11964 3869 11964
      3871 11965 3876 11968

$$

CJ

Area Forecast Discussion
National Weather Service Reno NV
157 PM PDT Wed May 31 2023

.SYNOPSIS...

Isolated to scattered showers and thunderstorms anticipated today
and Thursday, followed by lesser storm chances Friday into the
weekend. Temperatures will warm to slightly above average this
weekend, exacerbating snowmelt rates. Unsettled weather is favored
to return to the region next week.

&&

.DISCUSSION...

Latest radar observations reveal a few thunderstorms have formed in
the last few hours in Mono and N Washoe counties, providing a couple
strikes of lightning. Meanwhile, an expansive cumulus field is
apparent from NE CA into Washoe county per visible satellite.
Elsewhere, cumulus continues to bubble along the regional higher
terrain. The 18Z REV sounding depicts an unstable profile with a
residual capping inversion near 700 mb. Additionally, a dry layer
beneath 500 mb is noted in the sounding, which coupled with the
low-level inversion, is likely preventing local convection to
mature due to entrainment. Ongoing surface heating and resultant
updrafts will soon overcome these limiting factors, though
suggests storm initiation will be slightly delayed. Still,
isolated to scattered showers and thunderstorms will develop in
the next several hours, the strongest of which will be capable of
strong outflow gusts, small hail, and cloud-to-ground lightning.
Fortunately, storm motions will a bit more swift today and will
preclude a greater flash flood risk, but brief heavy downpours and
localized flash flooding remain possible today. Flash flooding is
a particular concern in/below burn scars and/or where prolonged
storm training occurs. Convective activity will continue into the
evening before diminishing with a few rain showers lingering
post-sunset.

The near-term synoptic pattern will feature an upper compact cyclone
slowly evolving from southern California to the Four Corners region
within the next 24 hours. Meanwhile, a subtle shortwave trough will
deepen as it approaches the West Coast before residing over the
Oregon/N California/SW Idaho vicinity through early Friday.
Attendant west to southwesterly flow aloft will develop across the
region early Thursday, slightly displacing rich moisture further
east towards the Basin and Range. The introduction of drier air
aloft will likely limit storm coverage Thursday, especially for the
western periphery of the region where moisture is depleted. With
that being said, the aforementioned shortwave will allow upper
divergence and subsequent large scale ascent to overspread portions
of the region while also providing a bit stronger bulk shear. The
overlap of most favorable upper dynamics and convective initiation
may be enough to sustain a couple stronger thunderstorms Thursday
afternoon, although coverage will be much more isolated compared to
previous days. Showers and thunderstorms will begin early Thursday
afternoon before activity tapers off shortly after sunset.

The shortwave perturbation will lift north of the state Friday,
allowing for a transient ridge to build overhead and stick around
into the weekend. Chances for showers and storms will be largely
diminished for this period as a result, with blended guidance
suggesting only a 10-20% chance of storms. Widespread warming will
accompany the high pressure aloft as temperatures warm a few degrees
each day this weekend. This may reinvigorate snowmelt rates and
increase flooding potential. Fortunately, ensembles favor cooler
weather for next week, but also signal a return of unsettled, stormy
weather that we've grown accustomed to as of late.

-Salas

&&

.AVIATION...

Another active thunderstorm day today, however, there will be
lesser coverage as compared to yesterday. There's a 30% chance for
a storm to form at or in the vicinity of KTRK/KTVL/KRNO/KCXP/KMEV
with a 60% chance around KMMH through 03z this evening. Scattered
showers and storms will linger for areas east of a Yerington-
Pyramid Lake line through ~06z.

Greatest storm risk will be localized heavy rainfall bringing low
ceilings and visibility in addition to terrain obscuration. Storms
may also produce gusty and erratic outflow winds up to 45 kts,
small hail and plentiful lightning.

Storm chances decrease on Thursday to 15-25%, mainly focused in NE
CA and western Nevada east of Highway 395, with a 10-15% chance
Friday and Saturday, mainly focused in the Sierra.

The only other item of note is a 80% chance for fog development
at KTRK 11z-15z each night/early morning. -Dawn

&&

.HYDROLOGY...

While the overall flash flood risk this afternoon is lower
compared to the previous two days, isolated locations could see
short bursts of heavy rain from any storms that do develop. Burn
scars, steep canyons, and smaller streams in the Sierra and far
western Nevada are among those areas most vulnerable to flash
flooding.

Little change is expected with the current river stages for the
next few days, as moderate flooding continues along the East Fork
and mainstem Walker River, with elevated flows and minor flooding
for other portions of the Walker River system. This will likely be
a long-duration concern as we continue to melt the record
snowpack, so be sure to heed river safety any advice from local
officials.

The other mainstem river to watch will be the Humboldt River as
elevated flows continue to slowly move downstream, with the latest
forecast at Imlay approaching minor flood stage by the weekend.
MJD/Dawn

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

Special Weather Statement
National Weather Service RENO NV
1239 PM PDT Wed May 31 2023

CAZ070>073-NVZ001>005-010600-
Surprise Valley California-Lassen-Eastern Plumas-
Eastern Sierra Counties-Greater Lake Tahoe Area-Mono County-
Mineral and Southern Lyon Counties-Greater Reno-Carson City-
Minden Area-Western Nevada Basin and Range including Pyramid Lake-
Northern Washoe County-
Including the cities of Cedarville, Eagleville, Fort Bidwell,
Portola, Susanville, Westwood, Sierraville, Loyalton,
South Lake Tahoe, Tahoe City, Truckee, Markleeville, Bridgeport,
Coleville, Lee Vining, Mammoth Lakes, Hawthorne, Yerington,
Smith Valley, Mina, Schurz, Stateline, Glenbrook,
Incline Village, Sparks, Verdi, Gardnerville, Virginia City,
Fernley, Fallon, Lovelock, Silver Springs, Nixon, Imlay, Empire,
and Gerlach
1239 PM PDT Wed May 31 2023

...Scattered Showers and Thunderstorms This Afternoon and
Evening...

* Scattered showers and thunderstorms are expected again today
  areawide, with a few locations possibly recieving heavy
  rainfall.

* Hazards include possible localized flash flooding, strong wind
  gusts to 50 mph, small hail, and frequent lightning. Any storms
  that form over area lakes could produce unsafe and choppy lake
  conditions.

* If you are outdoors today, keep your eyes on the sky. Head
  indoors if you hear thunder. If you can hear thunder, you are
  close enough to be struck by lightning. If you encounter flooded
  roads, do not drive your vehicle through them.

http://weather.gov/reno